A plesiosaur (pronounced /ˈpliːsiəsɔər/; Greek: plēsios/πλησιος 'near' or 'close to' and sauros/σαυρος 'lizard') was a type of carnivorous aquatic reptile (mostly marine but also sometimes freshwater). After their discovery, plesiosaurs were somewhat fancifully said to have resembled "a snake threaded through the shell of a turtle", although they had no shell. The common name "plesiosaur" is applied both to the "true" plesiosaurs (Superfamily Plesiosauroidea), which include both long-necked (elasmosaurs) and short-necked (polycotylid) forms, and to the larger taxonomic rank of Plesiosauria, which includes the pliosaurs. The pliosaurs were the short-necked, large-headed plesiosaurians that were the apex predators for much of the Mesozoic.
Plesiosaurs (sensu Plesiosauroidea) appeared at the start of the Jurassic Period and thrived until the K-T extinction, at the end of the Cretaceous Period. While they were Mesozoic reptiles derived from a common Diapsid stock that lived at the same time as dinosaurs, they were neither dinosaurs nor Archosaurs.
Plesiosaurs had a broad body and a short tail. They retained their ancestral two pairs of limbs, which evolved into large flippers. Plesiosaurs evolved from earlier, similar forms such as pistosaurs or very early, longer-necked pliosaurs. There are a number of families of plesiosaurs, which retain the same general appearance and are distinguished by various specific details. These include the Plesiosauridae, unspecialized types which are limited to the Early Jurassic period; Cryptoclididae, (e.g. Cryptoclidus), with a medium-long neck and somewhat stocky build; Elasmosauridae, with very long, inflexible necks and tiny heads; and the Cimoliasauridae, a poorly known group of Cretaceous [and post-Cretaceous?]forms. According to traditional classifications, all plesiosaurs have a small head and long neck but, in recent classifications, one short-necked and large-headed Cretaceous group, the Polycotylidae, are included under the Plesiosauroidea, rather than under the traditional Pliosauroidea. Size of different plesiosaurs varied significantly, with an estimated length of Trinacromerum being three meters and Mauisaurus growing to twenty meters.
And since we were on the subject before already, it is best to refer back to an earlier blog entry , quoting a longer article by Cameron McCormick:
There is at least one plesiosaur with what appears to be an adaptation for vertical movement in its neck. A juvenile specimen (only 700 mm, 28 inches in length) of the lower Cretaceous Leptocleidus had steeply angled zygapophyses in its cervical vertebrae which suggest the capacity for vertical movement (Kear 2007). The degree of flexibility was not mentioned, but it was apparently different enough from other taxa to suggest different prey types (Kear 2007). I feel that I am obliged to mention that [Leptocleidus is a Polycotylid] with the pliosaur-type morphology, apparently unlike many of its relatives (O'Keefe 2002). Leptocleidus doesn't seem to be too terrible short necked (as depicted above), it still had >20 cervicals and Fig. 6 of Kear 2007 shows the neck to be about twice the length of the head. Steeply angled cervical zygapophyses are unique as far as I can tell (which isn't very far), but I think it would be interesting to see if other attempts at "pliosaurs" and/or other juvenile Leptocleidus had this feature. Australian fossils of freshwater plesiosaurs are not strongly informative of taxonomy for the most part, but interestingly some suggest Leptocleidus (Kear 2006). Maybe having an unusually flexible neck in the vertical plane is useful for living in shallow near shore marine, brackish and freshwater environments - the juvenile in question was from marine deposits. Also problematic is that freshwater plesiosaurs in Australia were apparently subjected to cold to near-freezing conditions according to Kear (2006) - I couldn't imagine a 28 inch juvenile managing that. Freshwater plesiosaurs are potentially very interesting, they've been found worldwide from the early mid-Jurassic to the Late Cretaceous by the way, and I'd be curious about any morphological adaptations...
Back to plesiosaur necks, how flexible are they anyways? The genesis of this post was a paper by Zammit et al. (2008) which rigorously examined just that in the elasmosaur Aphrosaurus. The authors created life-sized 2D models of the vertebrae in dorsal and lateral view and used the minimum and maximum amount of intervertebral cartilage to create a possible range (Zammit et al. 2008). Models were also made of a boid, snake-necked turtle and sea lion for comparison - these tended to produce slight underestimates (Zammit et al. 2008*). It turns out that Aphrosaurus could bend its neck 87–155° in the dorsal plane - far from the 360°+ needed for a swan-like posture - and motion in the ventral plane (75–177°) and lateral plane (94–176°) appears to have been greater (Zammit et al. 2008). The authors mention an unpublished master's thesis which showed a similar pattern from Cryptoclidus and Muraenosaurus (both cryptoclidids) and noted that the vertebral centra in those genera had concave articular faces and rounded lateral margins, imply more vertebral movement (Zammit et al. 2008). Exact figures were not given, but the vertebral count (~40) was lower so the cryptoclidid necks are not necessarily more flexible overall. [Other studies do confirm that the Plesiosaurs with the medium-length necks have enough vertical movement to assume the "stretched-S" and "Periscope" postures reported in modern Sea-serpent reports. The modern reports also imply the same graded flexibility from front to back that such plesiosaur necks show. This turns out to be mechanically necessary for swimming at speed with a flexible neck pointed straight ahead]
*Zammit, Maria et al. 2008. Elasmosaur (Reptilia: Sauropterygia) neck flexibility: Implications for feeding strategies. Comparative Biochemistry and Physiology, Part A 150, 124-130
The Polycotylidae was separately chosen as the most likely source for the modern sightings of the smaller "Marine saurians" of the Ambon SS type,which in turn seem to be related to the creature known from a carcass in West Africa known as "Gambo". And so it seems, as Tyler Stone suggests, the Plesiosaurs which survived into modern times are both related, but one type is from a long-necked (Dolichodeire) family with a medium-loong neck, generally similar to Cryptoclidus, but a surviving related line is a secondarily shorter-necked Plesiosaur type related to the Polycotylids.
And it seems that the medium-length-necked surviving type also carried foreward adaptations making it able to tolerate both coldwater and freshwaters better than the more specialized Elasmosaurs.
Back when I was making up my Yahoo Cryptozoology group in 2006, it had started out as the Cryptozoology exchange and it had as its mascot "CryptoClyde", an individual of the Plesiosaur Cryptoclidus, such as was featured on the series Walking With Dinosaurs. Included in the group since the beginning was the pasteup shown here which illustrated how Cryptoclidus was similar in size and proportions to the descriptions of the Loch Ness Monster such as the sighting of the Creature on land by Arthur Grant indicated in the sketch above (from Tim Dinsdale's book Loch Ness Monster in 1960, and redrawing the illustration from Rupert T. Gould's book.)
Saturday, January 09, 2010
Frankly, I do not like the way the head and neck in the 'Surgeon's photo' are aligned if it is actually a plesiosaur, but then perhaps current theory on the flexibility of Plesiosaur necks does not cover living Plesiosaurs, n'est-pas? I also did a very exhaustive comparison of the head and neck in the photo to various kinds of waterbirds native to the area and none of them match at all well. It is the opinion of both Mackal and Coleman that the photo is authentic but represents a bird in the water. Such a bird must therefore be an unknown animal in itself.
There have been attacks made on both the 'Surgeon's Photo' and on Rhine's underwater photo at Loch Ness, most infamously with the assertion that Christian Spurling confessed to hoaxing the 'Surgeon's Photo' on his deathbed. Christian Spurling's account 'frames' the Daily Mail for hoaxing the photo to boost readership and is a libelous statement. Christian Spurling did not make a deathbed declaration and the account shows that he had no real knowledge of the photos in question - specifically the fact that there was more than one photo, with the object in different configurations, and not possibly the same object photographed twice.
There have also been statements made that a toy submarine made of materials at hand in the 1930s with a monster's-head superstructure would be top-heavy and tip over rather than stay afloat. A rather more peculiar problem is that there seems to have been no model he could have copied to look like the 'Sea Monster' in the photo: I have not seen any previous Plesiosaur reconstructions that actually match it. After the image of the photo was established in the imagination of the public, it seemed obvious to say that "I made a model of how the Loch Ness Monster looked" but it was not possible to say that before hand!
As to the Rhines AAAS underwater photo from the mid-1970s, it has been criticised by saying the head is not obviously continuous to the neck and that it needs to be aligned in the vertical plane. The critics that say this then go on to re-orientate the photo in the horizontal plane, inverted of its usual orientation. They then say it is a photograph of the bottom. It does not match the other photos more obviously showing the bottom, but the real problem is that saying this destroys their own argument. If the photo is indeed meant to be horizontal, then there is no reason why you need to say it must be vertical, and if it represents the bottom, then the tow parts really are continuous and the apparent break is only a trick of the shadows. Which is what supporters had been saying all along.
I am not saying that the 'Surgon's Photograph' is necessarily NOT a hoax; what I am saying is that it is consistent and that part could not have been known before hand. And in the matter of analysis I defer to LeBlond.
CRYPTOZOOLOGY vol. 1, winter 1982
"An Estimate of the Dimensions of the Lake Champlain Monster from the Length of Adjacent Waves in the Mansi Photograph" Paul H. LeBlond, p. 54
CRYPTOZOOLOGY vol. 6 , 1987
"The Wilson Nessie Photo: A Size Determination Based on Physical Principles" Paul H. LeBlond and Michael J. Collins, p. 55
Additional note: Many sources attribute a date of April 1 to the Wilson photo. The date was meant to be April 19, and what had happened was that one popular source had printed the '19' at the end of one line of text and the last digit '9' had fallen off the end of the line of type. This happened in Gould's book The Loch Ness Monster and Others, and I own a copy.
CFZ REPRINTFriday, January 08, 2010
DALE DRINNON: On "Discosaurus" and the possibility of Plesiosaurian Survival
Joseph Leidy had written several articles about the earliest finds of Plesiosaurs in North America, and one of them was the disputed 'Discosaurus' in Alabama, possibly originating from the same beds as 'Zueglodons' (Basilosaurus). He was writing in the 1850s and one of the comparable early finds was from the Greensands of New Jersey, thought to have been of Late Cretaceous age. The specimens in this case were named 'Cimoliasaurus'; however, some of them turned out to be cetacean vertebrae of probably Pliocene age, probably some sort of a dolphin.
However, this was some of the vertebrae and not all: Leidy did think the other vertebrae were legitimate and were of that genus, and probably related to that 'Discosaurus.' The different vertebrae had been found together in the same stratum in the same area
However, it seems that both genus names are invalid. 'Cimoliasaurus' has been described as a 'garbage taxon' and several nondescript fossils from Europe and Australia have also been ascribed to this genus, much in the same way as the early tendency to call all early canivorous dinosaur finds 'Megalosaurus'
In this case the really interesting thing is that the New Jersey fragmentary Plesiosaur is found in association with Pliocene dolphin fossils, mixed up together and only separated out later, and the Alabama fossils Leidy considered probably the same genus are labelled as coming from the Eocene zueglodon beds. In the case of the New Jersey Greensands, there is independant evidence that they are not only Cretaceous but also Tertiary: another site gives a paper in which several genera of O. C. Marsh's 'Cretaceous' birds from the New Jersey Greensands are actually of Eocene date or later.
[UPDATE: a Facebook Friend of mine also sent in a diffeent article identifying what looks like teeth from a crabeater seal (A true seal that still lives in Antarctica) from the same New Jersey Greensands stratum: if this is the case, The tooth in question was also illustrated by Leidy in the PNAS of 1851 and described under the same name as the exsting crabeater seal, remarking that the Greensand layer had previously been called Cretaceous, it must reall be Miocene.The purported PostCretaceous Plesiosaur thus coevxisted alongside dolphins and seals of the modern type, according to the original publisher of the find.-DD]
The characteristics of these fossils has placed them tenatively in the same family as Cryptoclidus and Muraenosaurus, and they were thought to have been like the Elasmosaurs but with shorter necks. This is also along the lines of what the surviving Plesiosaurs would have to have been to give rise to our Long-necked Sea-serpents: long-necked, but not excessively long-necked, not so specialised as the extreme Elasmosaurs, and generalised enough to be versatile, possibly enough so that they could pursue other avenues of evolution that became open to them.
That makes a good deal of sense and I am willing to arrange the theory of Plesiosaurian survival on those terms alone.
Dale Drinnon said...
It is important to bear in mind that the name "Discosaurus" was invalid even as that name was given to it, that name had previously been given to something else. So the putative Post-Cretaceous Plesiosaur is officially nameless at this point.6:27 AM
There is more on Discosaurus pssibly being from Eocene deposits in th 1981 book "Fossil Vertebrates of Alabama"
I did not see Scott's comment at the time but he is absolutely right and that book was in fact one of my sources.
Descriptioninternal nares were set forward, and the nostrils were relatively small. At up to 8 metres (26 ft) long, Cryptoclidus was a medium-sized plesiosaur. [Other relatives were up to perhaps twice as long]
PaleobiologyDue to their seal-like body plan, small plesiosaurs such as Cryptoclidus have been depicted as amphibious animals instead of fully marine reptiles. Despite looking clumsy and cumbersome, in water it would have been relatively graceful, using all four limbs as paddles, to swim and hunt its prey. It may have laid eggs in sand, but this is only conjectural.
The fragile build of the head and teeth preclude any grappling with prey, and suggest a diet of small, soft-bodied animals such as squid and shoaling fish. Cryptoclidus may have used its long, intermeshing teeth to strain small prey from the water, or perhaps sift through sediment for buried animals.
The size and shape of the nares and nasal openings have led Brown and Cruickshank (1994) to argue that they were used to sample seawater for smells and chemical traces.
The type species was initially described as Plesiosaurus eurymerus by Phillips (1871). The species name "wide femur" refers to the forelimb, which was mistaken for a hindlimb at the time.
The tail is elsewhere reconstructed as having such fins both above and below it
Now to continue onto the subject of surviving Pterosaurs, I shall reprint a guest blog from Texas Cryptid Hunter in 2010
Thursday, September 9, 2010
Pterosaurs and Thunderbirds
Alton has been very supportive of this blog and has offered several very helpful suggestions regarding how to make it better. When he told me he had written up a piece on the possibility of living Pterosaurs/Thunderbirds I knew it would be a great fit for this blog. Alton's piece is below:
Pterosaurs and Thunderbirds
A recent article at Salem-News.com related startling claims from explorers searching for pterosaurs in Papua New Guinea. Young Earth Creationists have long espoused the theory that pterosaurs live in that region, and expeditions have been repeatedly mounted to document their existence with the notion that such a discovery would serve to discredit evolutionary theory.
The explorers, Jim Blume and David Woetzel, president of “Genesis Park,” have collected eyewitness accounts of living pterosaurs “from frightened natives,” and claim to have seen the creatures themselves. Woetzel even shot video of a flying “pterosaur” in broad daylight. His video accompanies the Salem-News.com article. http://is.gd/eVsGZ
[In fact a good many "Pterosaur" reports from around New Guinea can be shown to be Frigate birds and this also is true of representations in artwork -DD]
Unfortunately, the video clearly shows a frigatebird, a large pelagic fish eating bird that obtains most of its food while flying, not a pterosaur. Five species of frigatebird are found throughout the world’s tropical oceans. Frigatebirds typically breed on remote oceanic islands and are consummate aerialists, capable of spending weeks in continuous flight and often ranging far from land.
While this blatantly obvious conclusion regarding the identity of the bird does not, in itself, preclude the possibility that some “frightened natives” have seen living pterosaurs, it does present doubts regarding the reported sightings of Blume and Woetzel. The purpose of this article, however, is to put a Texas twist on the issue of misidentifications, not to delve into the existence of pterosaurs in the South Pacific.
Unusually large mysterious flying creatures have long been reported from the Lone Star State. Just as is the case in Papua New Guinea, these seemingly inexplicable sightings are sometimes ascribed to pterosaur-like creatures. Others are sometimes called Thunderbirds, an evidently generic term applied to what appear to be huge birds that are otherwise rarely seen. A high percentage of these sightings originate in the southern part of Texas along the Mexican border. Author Ken Gerhard chronicles these kinds of sightings in his 2007 book “Big Bird! Modern Sightings of Flying Monsters.” Is it possible that some of these flying monsters are misidentified frigatebirds?
Frigatebirds are stiking creatures. In fact, the frigatebird species most likely to be observed in or near Texas is named the Magnificent Frigatebird (Fregata magnificens). They have huge wingspans at seven and a half feet, comparable to those of Bald Eagles. By comparison, a frigatebird would seem to dwarf the familiar Red-tailed Hawk and its four-foot wingspread. The frigatebird’s size and unusual appearance would instantly attract attention, especially if it were to be seen in desert or prairie environments, far from its normal haunts in the farthest reaches of the open sea. As unlikely as this may appear at first glance, frigatebirds DO sometimes wander inland.
Mlodinow (1998) summarizes the occasional meanderings of frigatebirds into the American interior. He states that Magnificent Frigatebirds have been reported as far inland as Colorado, more than 700 miles from the nearest saltwater. There are eight frigatebird records for Oklahoma and four from Kansas, one a mere sixty miles from Nebraska. New Mexico has six records.
It should be obvious that, given the above records, frigatebirds also can be seen away from the ocean in Texas. However, even though it is not considered all that unusual to see frigatebirds along the Texas coast or in pelagic regions (Mlodinow characterizes them as uncommon, but not rare, summer visitors), records of the birds more than fifty miles from the coast “are exceedingly scarce.” All these records occurred in the fall and “were related to hurricane or tropical storm activity.”
All in all, the typical Texan would not be expected to see a frigatebird in his or her lifetime and would be even less likely to know what they were seeing. The fact that these impressive birds, with their singular appearance, range rarely and unexpectedly into unfamiliar domains could account for some of the reports from baffled witnesses who mistakenly relate their sightings to extinct and mysterious creatures.
4 September 2010
Aym, Terrence. 12 Aug. 2010. Dinosaur Found Alive: Two Species Recorded in Papua New Guinea. Salem-News.com. http://www.salem-news.com/articles/august122010/live-dinosaur-ta.php
Mlodinow, Steven G. 1998. The Magnificent Frigatebird in Western North America. Field Notes (Now North American Birds) Vol. 52(4): 413-419. http://elibrary.unm.edu/sora/NAB/v052n04/p00413-p00419.pdf
Genesis Park http://www.genesispark.com/genpark/home.htm
Pterosaur Adventures http://www.creationinthecrossfire.org/Pterosaur%20Adventures.htm
The Marfa lights, also known as the Marfa ghost lights, have been observed near U.S. Route 67 on Mitchell Flat east of Marfa, Texas, in the United States. They have gained some fame as onlookers have ascribed them to paranormal phenomena such as ghosts, UFOs, or Will-o'-the-wisp, etc. However, research suggests that most, if not all, are atmospheric reflections of automobile headlights and campfires.Actually, Ghost Lights, Spook lights or Orbs (in the past identified as flying dragons also) are ae problem that is worldwide in scope:
In 1995, a young boy in northeastern Texas witnessed the strange behavior of a featherless flying creature hovering just a few feet above the ground. Aaron Tullock had the same problem as other eyewitnesses of living pterosaurs: Nobody believed his encounter. But an objective evaluation of his, and other’s, descriptions of the flying creatures—that reveals the obvious words that should be used: “pterodactyl,” or “pterosaur,” or “dragon.”
I picked this thing up in Mexico as part of my trip last year and despite the proto-post languishing for the best part of a year I have been re-inspired to write about it thanks to some photos of a colleague of mine. First off, what’s wrong with this? Well, anyone who has read my ‘top 10’ pterosaur mistakes will be familiar with most of them already. But in short:
The head is too small (of if you prefer the body is too big)
The shape of the crest is wrong
The neck is too short
There’s no propatagium / pteroid
The fingers face the wrong way and are the wrong lengths
The wing finger is too short
It has bat wings (and by extension some six fingers)
The wings have scales on them
The shape of the body is wrong
The legs are too short
It has a weird reversed toe
There is no uropatagium
There is a long tail
The tail vane should not be present, and even if you want to argue for a rhamphorhynchoid tail, the vane is the wrong shape.
In other words, this is really, really bad. I’m honestly not sure I’ve ever seen worse and I have looked. It pretty much fits every ‘top 10’ of bad pterosaurs which in itself is quite and achievement. However, the important thing here that I want to note is not how bad it is, but the fact that it came in a big pack of dinosaurs most of which were actually pretty good. OK, so the colours were lurid and most were a bit too upright in stance so they balanced on their tails, but really the proportions and details were about right (raptorial claw, long arms and stiff tail for the dromaeosaur, huge skull and just two fingers for the tyrannosaur, non-dragging tail for the sauropod and so on). Why then such a disaster when we reach the pterosaur?
I have touched on this before, but I think it is ultimately an artefact of public perception. Thanks largely due to Jurassic Park, but also any number of associated projects (other dinosaur films, new books, documentaries etc.) that spawned from its popularity, dinosaurs have had a new lease of life. The public (like it or not) have been exposed to lots and lots and lots of ‘modern’ upright, feathered, active dinosaurs. As such, if only subconsciously, they have a new perception of dinosaurs.
However, the pterosaurs seem not to have enjoyed the same shift in perception. They still lumber about with bat wings and scaly bodies, perched on tree branches or gliding through the air. I’m not foolish enough to think that pterosaurs will ever get the attention that dinosaurs do (and I’m happy to admit that at some level they don’t deserve that attention – the average dinosaur is more interesting and / or important than the average pterosaur) but this in itself is odd. To many people, pterosaurs *are* synonymous with dinosaurs so you would think that they might get dragged into the 21st century of public perceptions if only by accident. Even if not, many people accept and recognise that our understanding of dinosaurs has and continues to change rapidly, yet bizarrely they seem not to realise that this *also* happens to all the other prehistoric beasties.
It is I think an odd situation. The public seem to have accepted a ‘new’ vision of dinosaurs with all that entails while steadfastly refusing to budge on anything else, including pterosaurs which many consider to be dinosaurs. It’s a rather odd state of affairs and leaves us with this terrible pterosaur in an otherwise satisfactory collection of cheap dinosaur toys. I’m forced to conclude that, sadly, it may simply be that the average member of the pubic pays so little attention, and gives so little thought, to anything not explicitly put in front of them (be it in the cinema or a textbook) that they miss the point that lots of research on all things is going on all the time. This (I guess) filters down to the point that anyone not actively interested in pterosaurs or palaeontology as a whole might not be aware of this, to the point that even someone designing model dinosaurs knows about dromaeosaur claws, but not pterosaur wings.